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A.-P. de Candolle: une passion, un Jardin

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Conservatoire et Jardin botaniques de la Ville de Genève

WelcomeScientific ActivitiesProjects

Palms (Arecaceae) systematics

This program focuses in the study of the palm family (Arecaceae) incorporating disciplines ranging from taxonomy, morphology and anatomy to floristics and conservation. Different aspects on the biology of the palm family are explored with the aim of better understanding its evolution and taxonomic relationships at higher taxonomic ranks (tribes, subtribes). Nevertheless, the study of genera especially interesting from a phylogenetic perspective (i.e. isolated or unresolved position, evidence of early branching events, etc) is not excluded. Floristic treatments are related to permanent field activities and conservation status assessment of critical taxa is considered as a side product of first-hand observations of wild populations. The program is axed in the research carried out by FS in the Laboratory of Micro-morphology of the CJB (fully settled on 2006) as well as on the more classical study of collections deposited in international herbaria. The herbarium and the library of the Conservatory and Botanic Gardens of Geneva play a key role for taxonomical purposes. All the projects associated to the palm program have strong links with the master program of the Faculty of Science of the UniGe, from which several students are recruited every year. Full advantage is also obtained from the Swiss Federal Grant for foreign students. Most master projects are supported and collaborate with the Laboratory of Histology of the Faculty of Science (Dr. Michèle Crèvecoeur) and the Unity of Scanning Electronic Microscopy of the Natural History Museum of Geneva (Dr. André-Piuz). Ph.D. projects are co-advised in Latin American Universities, notably in two Venezuelan universities. Permanent collaboration with European students is favored through the annual meetings of the European Network of Palm Scientists (EUNOPS), from which FS is one of the founders and current active member. Active exchange of information is also maintained in Europe with the Laboratory of Palm Taxonomy of Kew Gardens (Dr. William Baker), Department of Biological Sciences of the University of Aarhus (Dr. Anders Barfod) and in USA with the Fairchild Tropical Garden (Dr. Carl Lewis) and the Montgomery Botanical Center (Dr. Larry Noblick). The backbone of the palm program is based on the almost 20 years of experience of FS studying this plant group, first restricted to floristics aspects of neotropical taxa and then extending to taxonomy and morphology from palms of other regions of the world. The wide range of subjects and disciplines covered by the program is highly characteristic of specialists dealing with the palm family. This plant group is extremely suitable for multidisciplinary approaches, which in turn favours collaborative work at an international scope. The program’s philosophy is ruled by 1.- production of high profile research, permanently validated by an international scientific community, and 2.- formation of human resources at university level, promoting long-lasting palm research in Switzerland and abroad.

Comparative data on reproductive structures in angiosperms has become critical for homology assessment and for testing their value in evolutionary biology. An accurate interpretation of the floral morphological complexity is, nevertheless, frequently hindered by the lack of both a robust taxonomic and phylogenetic framework. Unlike other monocotyledoneous families, palms benefit from benchmark family monographic accounts (e.g. Uhl and Dransfield, 1987; Dransfield and Uhl, 1998, Dransfield et al. 2008) that, even now, are being revised to incorporate the latest comparative biological findings. Phylogenetic studies based on molecular and non-molecular data are well advanced and have facilitated the erection of a new phylogenetic classification of the family (e.g. Uhl et al., 1995; Baker et al., 1999, Asmussen and Chase, 2001; Hahn, 2002, Asmussen et al. 2006, Baker et al. 2009). These studies have placed the palms as one of the best known groups among higher plants, providing a unique opportunity to test evolutionary hypotheses of morphological and anatomical reproductive features. Dioecy in palms has been reported in four of the five subfamilies currently recognized for the whole group, three of them represented in the Neotropics. This project explores the evolution of palm dioecy in Neotropical palms and takes advantage of the solid phylogenetic framework characterizing new world palms. Palms display an impressive diversity in the way they express their sexuality (Barfod & Uhl 2001). Flowers are either hermaphroditic or unisexual. Separation of sexual expression occurs in various ways in both time and space. Hermaphroditic flowers often pass through a male phase and a female phase (dichogamy). Unisexual flowers either occur together in tight clusters or they are separated spatially at either the inflorescence (monoecy) or gamet level (dioecy). In monoecious palms temporal separation of sexual expression also play a key role in assuring outbreeding. Monoecious palms such as the members of the Oil Palm genus Elaeis and the Sugar Palm genus Arenga produce pure male and female inflorescences in cycles or phases. Palm dioecy is much less known in the family and this project focuses in the study of its ontogenetic basis and evolution. Evolutionary pathways will be reconstructed by using current character mapping techniques on phylogenies including representatives of all tribes and subtribes studied. We will focus especially on the development of dioecy in neotropical taxa, which according to the latest molecular phylogeny has occurred in parallel in the tribes Chamadoreae (Arecoideae) and Ceroxyleae (Ceroxylodeae) and the subtribe Muritiinae (Calamoideae) (Asmussen et al. 2006). Our prediction that the ontogenetic basis of dioecy will be very different in the three groups will be tested by detailed comparison of anatomical preparations and scanning electron micrographs of different developmental stages. This project also aims to become a starting point towards the study of dioecy in the whole family, including critical taxa of Coryphoideae present in the old world. 2.- Acquisitions de données Collection of material Representatives of the three Neotropical palm groups displaying dioecy where selected and collection of developmental series fixed in FAA was carried out during field work in Venezuela in 2007 and Peru (planned for October, 2009). Herbarium vouchers have been obtained in all field trips organized so far and are deposited at G and AAU. Morpho-anatomical study Flowers at different stages of development are dissected under a stereomicroscope (Wild M3B). In the Scanning Electronic Microscope of the Natural History Museum of Geneva the specimens are dehydrated, critical-point-dried and sputter-coated with gold. Micrographs are obtained using a Zeiss DSM 940A scanning electron microscope (Orion 6.60 Imaging System). For the anatomical investigations, early buds and flowers are chosen and fixed with standard FAA. Sepals and petals are removed from some flowers investigated in order to facilitate the observation and infiltration of the inner organs. The flowers are then dehydrated and embedded in the resin of Technovit 7100 [2-hidroxyethyl methacrylate (HEMA)] (Heraus Kulzer Gmbh) and sectioning was carried out using a rotary microtome (Leitz 1512) at 5-10 µm thickness. Further details on this technique are explained in Igersheim and Cichocki (1996) and Stauffer et al. (2002). The sections are stained with toluidine blue and red ruthenium and mounted in Assistent-Histokitt mounting medium. Flowers are sectioned from the base towards the apex. Therefore consecutive levels in the sections refer to an acropetal sequence in the flowers. Photos of the anatomical sections are obtained using a microscope Leica DMIRE2 and a camera Leica DC 300F at the Faculty of Science of the University of Geneva. The collections and the permanent slides of the microtome sections are deposited at the Laboratory of Micromorphology of the Conservatory and Botanical Garden of Geneva. Herbarium vouchers are systematically deposited at G. The participation of FS and master candidates Nesly Ortega and Phaedra Sys (UniGe) is restricted to the morpho-anatomical study of developmental series in the already collected flowers of Chamaedoreeae (Arecoideae). PhD candidate Lorena Guevara (Venezuelan Central University), co-supervised by FS, is in charge of the study in members of Mauritiinae. The head of the project (Dr. Ander Barfod) will be in charge of the study in Ceroxylon (Ceroxylodeae) and the reconstruction of morphological character evolution through an examination of character state optimization.

1.- Description du projet The last treatment of the palms for the Venezuelan Palm Flora was published more than 30 years ago (Wessels Boer, 1978). Since then a large number of poorly known localities have been visited and an important amount of new collections has been gathered. Many preliminary updates on the family and new taxa (species, subspecies) have been published in the last 10 years by FS (Stauffer, 1999, 2000), originally based in the Venezuelan National Herbarium (VEN), and Andrew Henderson from the New York Botanical Garden (NY). These findings put in evidence that the Palm Flora of Venezuela remains poorly known, and additional efforts are required to increase our understanding on the native species present in the country. The publication of a palm flora is important for all the floristic and vegetation studies carried out in Venezuela, given the large representation of the palm family in the four ecoregions currently recognized for the country. This project will resume almost 15 years of floristic, taxonomic, ecologic, conservation and ethnobotanical studies carried out by FS on the Venezuelan palm species (see references at the end). This 6 years project aims to compile our current knowledge on the taxonomy, morphological diversity and the distribution of all Venezuelan native palm species. This compilation and related data analysis is critical in order to: 1.- update the description of all the genera and species, 2.- generate new identification keys and 3.- create distribution maps reflecting our current phytogeographical knowledge of the family. Main products of this project are the publication of a floristic treatment for the family and the publication of novelties resulting from a thorough study of complex taxa. 2.- Acquisitions de données Study of herbarium specimens About 3000 specimens have been studied (and databased) from the main Venezuelan herbaria: CAR, GUYN, HERZU, IRBR, MY, MYF, TFAV, UOJ and VEN, as well as international herbaria: G, K, M, NY, P, Z and US. Field work Field work on the frame of this project has been focused in unexplored areas of the northern Coastal Cordillera (field trip 2006) and the Orinoco Delta (field trip 2007). Other areas in the Venezuelan Amazon and the llanos where visited during 12 field trips between 1997 and 1999, period in which more than 600 palm collections were done One more trip to Venezuela will be probably necessary to revisit complex taxa of the genus Geonoma and Bactris in the cloud forests of northern region of the country. 3.- Traitement des données (méthodes.)* This project expects to produce an updated monographic treatment, which will be structured in the format of modern floristic treatments (description of the family, genera, species, identification keys, ecological notes). However, photos will replace usual line drawings, taking advantage of the rich collection of photos accumulated by FS, and distribution maps will be elaborated with GIS tools, making optimal use of the information databased by FS in 9 Venezuelan and 7 international herbaria (about 2500 collections). No guidelines have been established for the treatment of families in the Flora of Venezuela series; this is the reason why the guidelines of Flora Neotropica will be followed in order to guarantee homogeneous presentation of data. GIS tools will be employed in order to produce distribution maps for all species recognized in the flora. The exact method to be employed will be discussed with Cyrille Chatelain towards the end of the next year.

Uniqueness of the African palm flora The African palm flora is anomalous among other regional palm floras (Uhl and Dransfield, 1987; Dransfield et al., 2008). With only 65 species in 16 genera (vs. 992 spp./50 gen. in Malesia, 730 spp./65 gen. in the Neotropics, and 354 spp./43 gen. in mainland Asia), the palm diversity of Africa is depauperate given the size of the continent and the great extent of potential palm habitats. Despite its small size, however, the African Palm flora contains substantial diversity and endemism at higher taxonomic levels (Dransfield et al., 2008) Palms are conspicuous components of several vegetation types in the continent and are of great economic importance both to subsistence cultures and to highly organized commercial agriculture (Dransfield, 1988). Palms in Africa occur in perhaps greatest abundance in terms of species and individual in the low-lying swampland of the perhumid areas of West Africa (Letouzei, 1978). The most important recent analysis of the palm flora of Africa and its relationships is included in the paper of Moore (1973b) in which the palm floras of the forested regions of Africa and South America are analyzed and compared. The curiously diverse but sparse palm flora of Africa argues strongly for past diversity and widespread extinction. The great and well-known climatic vicissitudes (Moreau, 1966) of the past in Africa have had a profound effect on the palms, causing serious depletion of taxa adapted to humid tropical environments, while others, such as taxa in Borasseae (i.e. Borassus), adapted to more arid conditions may actually have been favoured and survive today with relatively rich representation (Dransfield, 1988). The remarkable low species numbers combined with the wide systematic spectrum of palms in Africa is supposedly due to extinction events during the Neogene, specifically, the result of aridification and retraction of rain forest in the Pleistocene. The current distribution of continental African palms was assessed by Blach-Overgaard et al. (2010). This study used a novel implementation of species distribution modelling (SDM) to assess the degree to which African continental-scale palm species distributions are controlled by climate, non-climatic environmental factors, or non-environmental spatial constraints. The study showed that, at a continental scale, climate constitutes the only strong environmental control of palm species distributions in Africa. Why are African rattans so interesting from a taxonomical, phylogenetic and economical point of view? Worldwide, there are around 650 species of rattan, representing 13 genera and these are concentrated only in the Old World Tropics (Dransfield, 1992). There are now known to be 22 species of rattans in the lowland tropical forests of Africa, represented by the endemic genera Laccosperma, Eremospatha and Oncocalamus, as well as a single representative of the Asian genus Calamus (Sunderland et al., 2005). The African endemic rattans form a strongly supported monophyletic clade at the base of the palm family (Baker et al., 2009). All three genera were proposed in subtribe Ancistrophyllinae, and together with subtribe Mauritiinae, already studied in detail in the frame of a PhD thesis co-supervised by Fred Stauffer, form the tribe Lepidocaryeae at the base of subfamily Calamoideae. The genera of Ancistrophyllinae are poorly known from a taxonomical point of view and their study is additionally important for our current understanding of character evolution in early divergent palm groups. The climbing palms or rattans of the Upper Guinean forests play also a significant role in the forest economy of the region through the utilization of the inner stems, or cane, for furniture and the manufacture of household commodities in many rural areas. Despite their economical importance the rattans considerable uncertainty has persisted with respect to their taxonomy. Recently, the taxonomy of this group was studied in detail and four new species have been described (Sunderland, 2002, 2003). Rattans are currently harvested from wild populations. The intensity of the exploitation has locally led to over-harvesting and a result the stocks of this important resource are seriously depleted (Sunderland et al., 2005). African rattans have long been recognized by donor agencies and national governments as having a potential role to play on the world market, as well as a great role within the regional Non-Timber Forest Products (NTFP) sector of Africa. As increased interest in being shown in the potential role of high value NTFPs to contribute to conservation and development, rattans are frequently mentioned as a product that could be developed and promoted in a useful way. However, the development of the rattan resource in Africa has, until recently, been hindered by a lack of basic knowledge about the exact species used, their ecological requirements and the socio-economic context (Sunderland, T. 2007). Main goals of our study Detailed characterization of the native palms of Ghana, with emphasis in their taxonomy, morphology, uses, distribution and conservation status. The final goal will be the publication of a field guide for the identification of palms in that country, offering critical tools for their identification using ecological and morphological data

Trithrinax is a small genus of palms that comprises 3-5 species and belongs to the subfamily Coryphoideae (Asmussen et al, 2006), tribe Cryosophileae (Dransfield et al, 2005). Species of Trithrinax are distributed in Bolivia, Brazil, Paraguay, Uruguay and Argentina (Henderson et al, 1995), where the stems are used in construction and the leaves for thatching and handcraft manufacturing (Henderson, 1995; Gibbons, 2001). The latest comprehensive revision of the genus Trithrinax was published about 80 years ago by Beccari (1931). Beccari´s revision included 5 species (T. acanthocoma, T. biflabellata, T. brasiliensis, T. campestris, and T. schizophylla), mostly separated according to the variation in the length of sepals, petals and styles. T. acanthocoma and T. brasiliensis were characterized by their short styles and the remaining three species having long styles (at least three times longer than the ovary). The genus has been superficially treated in the general floristic inventory of Neotropical palms published by Henderson et al. (1995), in which it is supposed to contain only three accepted species; the main characters useful for their identification in the field were based on the vegetative organs. Beside these efforts there has been no other taxonomical treatment on this group and this may be explained by the difficulties related to the collection of these palms (i.e. dry-xeric areas, arborescent habit, strongly armed stems). To increase the incomplete knowledge of Trithrinax, fieldwork, collection of new material, modern morphological and phylogenetic systematic analyses, and revision of type specimens, are needed. Trithrinax are now placed in the new tribe Cryosophileae (Dransfield et al. 2008), a monophyletic and well-supported group comprising nine other genera of the New World and 40 species with a center of diversity in the Caribbean region (Uhl et al, 1995; Baker et al, 1999; Asmussen & Chase, 2001; Hahn, 2002; Asmussen et al, 2006). However, relationships among the genera of this tribe are currently far to be resolved. To date the most comprehensive phylogenetic analysis of Cryosophileae was mainly focused on Caribbean taxa (Roncal et al 2008) and did not include Trithrinax and other genera endemic of the Amazon basin (i.e. Chelyocarpus) are extremely poorly represented. The aims of this study are to undertake a monographic treatment of the genus Trithrinax and to explore its relationships with other genera of tribe Cryosophileae, through a molecular phylogenetic analysis of the tribe using an exhaustive taxa sampling at the generic level and several molecular markers from the nuclear genome. In a more general context, this phylogenetic framework will also be used to reconstruct pattern of diversification and the biogeographical history of the Cryosophileae, especially to clarify the relationship between the continental (e.g. Trithrinax, Chelyocarpus) and the more diversified Caribbean lineages. The main objectives of this research are: To delimit species and perform a monographic revision of the genus Trithrinax based on morphological and molecular data (the later if informative). To sequence three single-copy nuclear markers PRK, RPB2 and Malate synthase (Roncal et al. 2008 , Lewis and Doyle 2001) for about 60 accessions representative of Trithrinax diversity and 37 other species belonging to the tribe Cryosophileae. To analyze DNA sequences and obtain a phylogenetic tree including most species of the tribe to test the monophyly of Trithrinax, resolution within the genus and its phylogenetic position in the tribe. To combine various data sources (phylogenetic, biogeographic, fossil and morphology) to reconstruct the diversification of the Cryosophileae in time and space.